Surfactant protein-A (SP-A) gene expression is developmentally regulated in fetal lung type II cells in concert with surfactant glycerophospholipid synthesis. In studies using transfected type II cells, we characterized a nuclear receptor element (NRE_SP-A, 5'-TGACCTTA-3') at -242 bp in the 5'-flanking sequence of human SP-A2 (hSP-A) gene that is essential for basal and cAMP-induced expression. NRE_SP-A has high sequence similarity to the consensus binding site for estrogen-related receptor (ERR). In the present study, we observed that ERR and , but not ERR, were expressed in human fetal lung type II cells. In vitro transcribed/translated ERR and bound to the NRE_SP-A; DNase I footprinting using bacterially expressed ERR revealed a single DNase I protected region that included NRE_SP-A. In transient transfection assays of COS-7 and primary cultures of lung type II cells, ERR acting through NRE_SP-A increased hSP-A promoter activity, while ERR had no effect. ERR overexpression in lung type II cells enhanced cAMP induction of endogenous hSP-A expression, while cotransfection of protein kinase A catalytic subunit enhanced ERR stimulation of hSP-A promoter activity in lung adenocarcinoma cells. Mice homozygous null for the ERR gene manifested decreased SP-A expression relative to wild-type and heterozygous littermates. The ERR-specific inverse agonist XCT790 inhibited cAMP induced hSP-A expression in human fetal lung type II cells in a concentration dependent manner, suggesting a role of peroxisome proliferator-activated receptor coactivator 1 (PGC-1). These findings suggest that ERR acting through NRE_SP-A is an important mediator of hSP-A gene expression and its induction by cAMP.